The Adafruit Trellis is an open-source backlight keypad driver system designed to work with the Adafruit 4×4 elastomer keypad and 3mm LEDs. Each tile handles keypress detection and LED control for a 4×4 grid over I2C, and up to 8 tiles can be connected together for a total of 128 buttons and LEDs using just 2 I2C wires.

The onboard I2C chip individually controls all 16 LEDs (on/off, no dimming) and reads keypresses with diode multiplexing to prevent ghosting. Each LED is driven with constant current, so you can mix and match any colours of 3mm LEDs. An Arduino or other microcontroller is required to control the Trellis — the PCB does not include any onboard processing.

Key Features

• 4×4 Keypad and LED Driver – Controls 16 LEDs and reads 16 button presses per tile
• I2C Interface – Simple 2-wire connection with 3 address jumpers for up to 8 unique addresses
• Tileable Design – Connect up to 8 tiles edge-to-edge (up to 128 buttons/LEDs) sharing power, ground, interrupt, and I2C lines
• Anti-Ghosting – Diode-multiplexed key connections for accurate multi-key detection
• Constant-Current LED Driver – Mix and match any colours of 3mm LEDs
• Flexible Layout – Tiles can be arranged in any configuration as long as each is connected via the 5 edge-fingers

Ideal For

• Custom MIDI controllers and music interfaces
• LED button grids and step sequencers
• Interactive control panels
• DIY macro keypads

Package Contents

• 1× Adafruit Trellis Monochrome Driver PCB (assembled, no LEDs or buttons)

Resources

• Adafruit Trellis Arduino Library (GitHub)
• Adafruit Trellis Learning Guide